1. Field of the Invention
The present invention relates to semiconductor packages and fabrication methods thereof and more particularly, to a semiconductor package and a fabrication method thereof for improving the product reliability.
2. Description of Related Art
With the rapid development of electronic industries, electronic products are developed towards miniaturization, light weight and high speed processing. Radio frequency (RF) chips are required in a lot of electronic products. For the purpose of miniaturization or high speed processing, RF chips are usually integrated with digital integrated circuits (ICs), digital signal processors (DSPs) or baseband (BB) chips.
Currently, there are various types of chip packages. To achieve a small surface bonding area, a plurality of chips are usually disposed on a substrate in a stack manner and electrically connected to the substrate through wire bonding. To facilitate the wire bonding, the chips are disposed with their active surfaces facing upward. A dummy chip or a paste adhesive or film is disposed between two adjacent chips, thus allowing bonding wires to have sufficient wire loops.
FIG. 1 is a schematic cross-sectional view of a conventional semiconductor package 1. Referring to FIG. 1, the semiconductor package 1 has a circuit board 10, an RF chip 12 disposed on the circuit board 10, a dummy chip 11 disposed on the RF chip 12, a semiconductor chip 14 disposed on the dummy chip 11, a plurality of first bonding wires 140 electrically connecting the semiconductor chip 14 and the circuit board 10, a plurality of second bonding wires 13 electrically connecting the RF chip 12 and the circuit board 10, and an encapsulant 16 encapsulating the dummy chip 11, the semiconductor chip 14, the first bonding wires 140, the RF chip 12 and the second bonding wires 13. Since a gap is provided between the semiconductor chip 14 and the RF chip 12 by the dummy chip 11, the second bonding wires 13 can be formed with a sufficient wire loop.
However, RF circuits of the RF chip 12 form a sensitive area easily affected by such as interferences and thermal factors, especially when the RF chip 12 is a high frequency chip or a wireless RF chip. As such, the flexibility of wiring and element arrangement is reduced and it becomes quite difficult to achieve a highly integrated wireless system in package (SiP) module.
Further, signals from the RF chip 12 and the semiconductor chip 14 arranged in a stack manner may interfere with each other and generate noises, especially when the RF chip 12 is a high frequency chip or a wireless RF chip, thereby seriously affecting operation of the semiconductor chip 14.
Therefore, there is a need to provide a semiconductor package and a fabrication method thereof so as to overcome the above-described drawbacks.